Phosphatidylserine/Prothrombin Antibody, IgG and IgM, Serum

Message

ORDERING GUIDANCE
Cardiolipin and beta-2 glycoprotein testing are the first-tier test options for most patients. Phosphatidylserine/prothrombin antibodies are considered part of the second-tier workup.

Test Code

PSPT

Alias/See Also

Epic: LAB14321
Mayo: PSPT

Second-tier phospholipid

CPT Codes
86148 x 2

Includes

Test Id	Reporting Name	Available Separately	Always Performed
PSPTG	PS/PT Ab, IgG, S	Yes	Yes
PSPTM	PS/PT Ab, IgM, S	Yes	Yes

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 0.5 mL

Minimum Volume

0.4 mL

Instructions

Centrifuge and aliquot serum into a plastic vial.

Transport Container

Plastic vial

Specimen Stability

Specimen Type	Temperature	Time	Special Container
Serum	Refrigerated (preferred)	21 days
	Frozen	21 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis	Reject
Gross lipemia	Reject
Gross icterus	OK
Heat Treated	Reject

Methodology
Enzyme-Linked Immunosorbent Assay (ELISA)

Setup Schedule

Wednesday

Report Available

2 to 8 days

Limitations

CAUTIONS
A diagnosis of antiphospholipid syndrome (APS) should not be based only on the presence of anti-phosphatidylserine/prothrombin antibodies. Results must be interpreted in the appropriate clinical context.

Anti-phosphatidylserine/prothrombin complex IgM antibodies have a lower risk for APS-associated thrombotic events compared to the IgG isotype in carriers.

A negative result for anti-phosphatidylserine/prothrombin IgG and IgM antibodies does not exclude the diagnosis of APS.

Anti-phosphatidylserine/prothrombin IgG and IgM antibodies are not yet included in the classification criteria for APS.

Reference Range

REFERENCE VALUES
Negative < or =30.0 U
Borderline 30.1-40.0 U
Positive > or =40.1 U

INTERPRETATION
A positive and persistent result for anti-phosphatidylserine/prothrombin complex IgG and/or IgM antibodies may be suggestive of a diagnosis of antiphospholipid syndrome (APS) in patients with evidence of arterial, venous, or specific pregnancy-related morbidities. These antibodies may also exist prior to the occurrence APS clinical manifestations as well as in patients with other systemic autoimmune diseases such systemic lupus erythematosus.

Anti-phosphatidylserine/prothrombin complex IgG antibodies have relatively higher correlations with positive results for lupus anticoagulant than the IgM isotype as well as significant risk for APS-associated thrombotic events compared to the IgM isotype in antiphospholipid antibody carriers.

A negative result does not exclude the diagnosis of APS, as other phospholipid/protein antibodies are also associated with this disorder.

Clinical Significance

USEFUL FOR
Preferred second-tier panel for the detection of IgG and IgM antibodies against phosphatidylserine/prothrombin complex in patients with strong suspicion of antiphospholipid syndrome (APS) who are negative for the APS criteria laboratory tests (lupus anticoagulant, IgG and IgM anticardiolipin/beta 2-glycoprotein I, and anti-beta 2-glycoprotein I antibodies)

May be useful for the evaluation of patients with prior positive lupus anticoagulant results who are on direct oral anticoagulant therapy

May be useful as a risk marker for thrombosis in antiphospholipid antibody carriers

CLINICAL INFORMATION
The 2023 American College of Rheumatology/European Alliance of Associations for Rheumatology antiphospholipid syndrome (APS) classification criteria includes an entry criterion of at least one positive antiphospholipid antibody (aPL) test within 3 years of identification of an aPL-associated clinical criterion, followed by additive weighted criteria (score range 1-7 points each) clustered into 6 clinical domains (macrovascular venous thromboembolism, macrovascular arterial thrombosis, microvascular, obstetric, cardiac valve, and hematologic) and 2 laboratory domains (lupus anticoagulant functional coagulation assays, and solid-phase enzyme-linked immunosorbent assays for IgG/IgM anticardiolipin and/or IgG/IgM anti-beta 2-glycoprotein I antibodies).(1) Cardiolipin is an anionic phospholipid that interacts with the protein cofactor beta 2-glycoprotein I. Lupus anticoagulant (LA) is an indirect assessment for the presence of antiphospholipid antibodies, which is evident in the in vitro prolongation of phospholipid-dependent coagulation.(2) Anticardiolipin and anti-beta 2-glycoprotein I antibodies are detected in solid-phases immunoassays using beta 2-glycoprotein I-dependent cardiolipin/or beta 2-glycoprotein I alone as substrate, respectively.(2,3)

There is evidence from multiple studies to suggest that patients with APS may develop autoantibodies to other phospholipid/protein complexes, specifically phosphatidylserine/prothrombin (PS/PT).(4-9) Like beta 2-glycoprotein-dependent I cardiolipin, PS/PT is a complex composed of the anionic phospholipid phosphatidylserine and the protein cofactor prothrombin. In a systematic review, Sciascia et al demonstrated that the presence of anti-PS/PT IgG antibodies is an independent risk factor for arterial and/or venous thrombotic events, with odds ratio (OR) of 5.11 (95% CI: 4.2-6.3).(4) A multicenter study showed that IgG anti-PS/PT were more prevalent in APS patients (51%) than in those without (9%), OR 10.8, 95% CI (4.0-29.3), p <0.0001.(5) Furthermore, a number of studies have shown clinical and laboratory evidence that PS/PT antibodies may be a useful second-line test for the evaluation of patients at-risk or suspected with suspected APS, particularly for those individuals with evidence of thrombosis or abnormal LA testing.(6,7) While anti-PS/PT antibodies were highly prevalent and correlated with other anti-PL antibodies, IgG anti-PS/PT conferred a high risk for thrombosis (8,9) but not for pure hematologic involvement.(9) These antibodies may also be seen in patients with other autoimmune diseases such as systemic lupus erythematosus.(5,8) In individuals who test positive for antiphospholipid antibodies without clinical features of APS (carriers), the cumulative incidence rate of thrombotic events has also been reported to be significantly higher for anti-PS/PT IgG positive than anti-PS/PT IgM positive subjects.(10)

Performing Laboratory
Mayo Clinic Laboratories - Rochester
3050 Superior Drive NW
Rochester, MN 55901

Additional Information
Phosphatidylserine/Prothrombin Antibody, IgG and IgM, Serum

Last Updated: March 15, 2024
Last Review: N. Wolford, March 15, 2024

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.